The present invention relates to a process for producing a mixture of 3- and 4-(4'-methyl-4'-hydroxyamyl)-.DELTA..sup.3 -cyclohexene carboxaldehyde in good yields and under relatively mild conditions; and the uses in perfumery of the products produced by such process.
The mixture of 3- and 4-(4'-methyl-4'-hydroxyamyl)-.DELTA..sup.3 -cyclohexene carboxaldehyde is a well known perfumery material having been produced by various processes including Diels-Alder reactions of acrolein having the structure: ##STR4## with myrcenol having the structure: ##STR5## at high temperatures in the absence of catalyst or at low temperatures in the presence of a Lewis acid catalyst as described in an application for U.S. Pat. No. 620,354, filed on October 7, 1975. The mixture of 3- and 4-(4'-methyl-4'-hydroxyamyl)-.DELTA..sup.3 -cyclohexene carboxaldehyde is indicated to be produced in U.S. Pat. No. 2,947,780 issued on Aug. 2, 1960, by means of reacting myrcenol in a sealed reactor and heating acrolein with myrcenol in a sealed reactor and heating the reaction mass to 150.degree. C for a period of time (e.g. 41/2 hours) accompanied by agitation. The reaction mass is then allowed to cool and the contents removed and subjected to fractional distillation.
U.S. Pat. No. 3,433,839 discloses a more complex process for preparing compounds having a structure similar to those prepared in the instant case. U.S. Pat. No. 3,433,839 discloses a process for producing a mixture of alicyclic hydroxyaldehydes which comprises:
I. photo-oxidizing myrcene to produce a mixture of its hydroperoxides; PA1 Ii. reducing the resulting mixture to produce a mixture of 2-methyl-6-methylene-3,7-octadiene-2-ol and 2-methyl-6-methylene-1,7-octadiene-3-ol; and PA1 iii. reacting the thus-obtained mixture with a dienophile selected from the group consisting of acrolein and crotonaldehyde at 100.degree. to 150.degree. C for 3 to 6 hours to produce at least one mixture of alicyclic hydroxyaldehydes selected from the group consisting of, where said dienophile is acrolein, 4-(4'methyl-4'-hydroxy-2'-pentenyl)-3-cyclohexene-1-carboxaldehyde and 4-(4'-methyl-3'-hydroxy-4'-pentenyl)-3-cyclohexene-1-carboxaldehyde, and where said dienophile is crotonaldehyde, 4-(4'-methyl-4'-hydroxy-2'-pentenyl)-6-methyl-3-cyclohexene-1-carboxaldehy de and 4-(4'-methyl-3'-hydroxy-4'-pentenyl)-6-methyl-3-cyclohexene-1-carboxaldehy de.
British Pat. No. 1,419,243 discloses a process for the manufacture of aldehydes including the aldehydes produced in the instant case of the generic formula: ##STR6## wherein the formyl group is present in either or both the 4- and 5- positions by hydrating an aminal of the formula: ##STR7## wherein the dimorpholine-methyl group is present in the 4- or 5-position, or a mixture of the 4- and 5-position isomers to the corresponding 4'-hydroxy compound and subsequently cleaving off the dimorpholino protecting group. It is indicated that the hydration of the aminal of the formula: ##STR8## can be carried out according to "methods known . . . for example, by treatment with a non-oxidizing mineral acid such as sulphuric acid, phosphoric acid or hydrochloric acid . . . e.g. 50-70% sulphuric acid, 60-70% phosphoric acid or 28- 33% hydrochloric acid." It is further indicated that the hydration can be carried out at a temperature of from approximately -20.degree. C up to +30.degree. C, preferably at approximately 0.degree. C to approximately 20.degree. C. The example on page 2 of British Patent 1,419,243 states that, when starting with 192 grams (1 mole) of myrac aldehyde which is a mixture of 3- and 4-(4'-methyl-3'-pentenyl)-.DELTA..sup.3 -cyclohexene carboxaldehyde, 107 grams (51% yield) of a mixture of 3- and 4-(4'-methyl-4'-hydroxypentyl)-.DELTA..sup.3 -cyclohexene carboxaldehyde (containing 35% of 3-(4'-methyl-4'-hydroxypentyl)-.DELTA..sup.3 -cyclohexene carboxaldehyde) is produced.
Kagami, Canadian Journal of Chemistry, 52:125(1974) reports the hydration of the morpholine enamine of myrac aldehyde having the structure: ##STR9## using 50% sulfuric acid. In Table 2 of this reference it is reported that myrac aldehyde per se is not hydrated to give compounds having the structure: ##STR10## in the presence of 50% sulfuric acid at -2.degree. to 10.degree. C.
Thus, nothing in the prior art shows the possibilities of proceeding directly from compounds having the structure: ##STR11## to compounds having the structure: ##STR12## without going through the extra costly step of tying up the carboxaldehyde moiety with such groups as the morpholine group. Arctander, "Perfume and Flavor Chemicals, Aroma Chemicals" by Steffan Arctander, published in 1969, Volumn II at 2162 states that myrac aldehyde is a useful perfumery material but that "the hydroxylated aldehyde known under the name "lyral" . . . is far more successful than the title aldehyde but is in no way olfactorily related to it." Nevertheless, Arctander shows no way of "hydroxylating" myrac aldehyde without going through the costly step of "tying up" the carboxaldehyde moiety as is shown in British Pat. No. 1,419,243 and other related prior art.